In a Multiple-Input Multiple-Output (MIMO) system, if a transmitter is able to be somehow informed of the channel information, the optimization on the transmitted signal can be available according to channel characteristics so as to improve the quality of receiving and reduce complexity requirements on the receiver. The feedback for channel information is usually achieved by the way of quantifying channel information in actual systems, so as to reduce feedback overhead, thus improving transmission efficiency of the system.
In Long Term Evolved (LTE) system, a codebook-based implicit Channel State Information (CSI) feedback method is adopted. User Equipment (UE, namely, terminal equipment) measures the downlink channels based on pilots and reports Rank Indication (RI) that downlink can support and Precoding Matrix Indicator (PMI) to a base station according to its own receiving processing algorithm. Meanwhile, UE further needs to report Channel Quality Indicator (CQI) of each codeword. Therein, during the calculation of CQI, UE assumes that the base station uses its recommended RI/PMI.
In LTE system, PMI is defined as follows:
For 2 antenna ports {0, 1} and corresponding RI value which is 1, the PMI value nε{0, 1, 2, 3} shall correspond to the codebook index n in υ=1 in the Table 1 below (a corresponding relationship of pre-coding matrix indicator information in LTE system with the codebook index in the codebook for 2 antenna ports);
For 2 antenna ports {0, 1} and corresponding RI value which is 2, the PMI value nε{0, 1} shall correspond to the codebook index n+1 in υ=2 in Table 1 below;
For 4 antenna ports {0, 1, 2, 3} and corresponding RI value which is 2, the PMI value nε{0, 1, . . . , 15} shall correspond to the codebook index n in υ=RI value in the below Table 2 (a corresponding relationship of pre-coding matrix indicator information in LTE system with the codebook index in the codebook for 4 antenna ports).
TABLE 1Codebook Rank index 1 20       1          2        ⁡      [                            1                                      1                      ]        1          2        ⁡      [                            1                          0                                      0                          1                      ]   1       1          2        ⁡      [                            1                                                  -            1                                ]        1    2    ⁡      [                            1                          1                                      1                                      -            1                                ]   2       1          2        ⁡      [                            1                                      j                      ]        1    2    ⁡      [                            1                          1                                      j                                      -            j                                ]   3       1          2        ⁡      [                            1                                                  -            j                                ]  —
TABLE 2CodebookRank υindexun12340u0 = [1 −1 −1 −1]TW0{1}W0{14}/{square root over (2)}W0{124}/{square root over (3)}W0{1234}/21u1 = [1 −j 1 j]TW1{1}W1{12}/{square root over (2)}W1{123}/{square root over (3)}W1{1234}/22u2 = [1 1 −1 1]TW2{1}W2{12}/{square root over (2)}W2{123}/{square root over (3)}W2{3214}/23u3 = [1 j 1 −j]TW3{1}W3{12}/{square root over (2)}W3{123}/{square root over (3)}W3{3214}/24u4 = [1 (−1 − j)/{square root over (2)}−j (1 − j)/{square root over (2)}]TW4{1}W4{14}/{square root over (2)}W4{124}/{square root over (3)}W4{1234}/25u5 = [1 (1 − j)/{square root over (2)}j (−1 − j)/{square root over (2)}]TW5{1}W5{14}/{square root over (2)}W5{124}/{square root over (3)}W5{1234}/26u6 = [1 (1 + j)/{square root over (2)}−j (−1 + j)/{square root over (2)}]TW6{1}W6{13}/{square root over (2)}W6{134}/{square root over (3)}W6{1324}/27u7 = [1 (−1 + j)/{square root over (2)}j (1 + j)/{square root over (2)}]TW7{1}W7{13}/{square root over (2)}W7{134}/{square root over (3)}W7{1324}/28u8 = [1 −1 1 1]TW8{1}W8{12}/{square root over (2)}W8{124}/{square root over (3)}W8{1234}/29u9 = [1 −j −1 −j]TW9{1}W9{14}/{square root over (2)}W9{134}/{square root over (3)}W9{1234}/210u10 = [1 1 1 −1]TW10{1}W10{13}/{square root over (2)}W10{123}/{square root over (3)}W10{1324}/211u11 = [1 j −1 j]TW11{1}W11{13}/{square root over (2)}W11{134}/{square root over (3)}W11{1324}/212u12 = [1 −1 −1 1]TW12{1}W12{12}/{square root over (2)}W12{123}/{square root over (3)}W12{1234}/213u13 = [1 −1 1 −1]TW13{1}W13{13}/{square root over (2)}W13{123}/{square root over (3)}W13{1324}/214u14 = [1 1 −1 −1]TW14{1}W14{13}/{square root over (2)}W14{123}/{square root over (3)}W14{3214}/215u15 = [1 1 1 1]TW15{1}W15{12}/{square root over (2)}W15{123}/{square root over (3)}W15{1234}/2
Wherein, Wn=I−2ununH/unHun, I refers to unit matrix of dimension 4×4, unH represents the conjugate transpose of un.
In Long Time Evolved Advanced (LTE-A) system, the codebook-based implicit CSI feedback method is further adopted. In order to improve the accuracy of PMI feedback, in LTE-A, a pre-coding matrix (W) is formed by merging two matrixes (W1 and W2); W1 and W2 are indicated by two PMIs respectively (the first PMI value, corresponding to W1; and the second PMI value, corresponding to W2).
The codebook in LTE version R8/9 is still used in 2 antenna ports and 4 antenna ports; W1 is defined as a unit matrix, while the first PMI value contains 0 bit of information, no feedback is required. Specifically, the corresponding relationship of pre-coding matrix indicator information in LTE-A system with the codebook index in the codebook for 8 antenna ports is shown is in Table 3 to Table 10.
Table 3 refers to codebook for 1-layer CSI reporting using antenna ports 15 to 22 (the codebook for 1-layer CSI reporting using 8 antenna ports (ports 15 to 22)), namely, Rank 1 codebook for 8 antenna ports in LTE-A system.
TABLE 3i2 i1 0 1 2 3 40-15   W            2      ⁢              i        1              ,    0        (    1    )    W            2      ⁢              i        1              ,    1        (    1    )    W            2      ⁢              i        1              ,    2        (    1    )    W            2      ⁢              i        1              ,    3        (    1    )    W                    2        ⁢                  i          1                    +      1        ,    0        (    1    )  i2 i1 5 6 7 890-15   W                    2        ⁢                  i          1                    +      1        ,    1        (    1    )    W                    2        ⁢                  i          1                    +      1        ,    2        (    1    )    W                    2        ⁢                  i          1                    +      1        ,    3        (    1    )    W                    2        ⁢                  i          1                    +      2        ,    0        (    1    )    W                    2        ⁢                  i          1                    +      2        ,    1        (    1    )  i2 i1 10 11 12 13 140-15   W                    2        ⁢                  i          1                    +      2        ,    2        (    1    )    W                    2        ⁢                  i          1                    +      2        ,    3        (    1    )    W                    2        ⁢                  i          1                    +      3        ,    0        (    1    )    W                    2        ⁢                  i          1                    +      3        ,    1        (    1    )    W                    2        ⁢                  i          1                    +      3        ,    2        (    1    )  i2 i1 150-15   W                    2        ⁢                  i          1                    +      3        ,    3        (    1    )        Therein    ⁢                  ⁢          W              m        ,        n                    (        1        )              =            1              8              ⁡          [                                                  v              m                                                                                          φ                n                            ⁢                              v                m                                                        ]      
Table 4 refers to Codebook for 2-layer CSI reporting using antenna ports 15 to 22 (the codebook for 2-layer CSI reporting using 8 antenna ports (ports 15 to 22)), namely, Rank 2 codebook for 8 antenna ports in LTE-A system.
TABLE 4i2 i1 0 1 2 30-15   W            2      ⁢              i        1              ,          2      ⁢              i        1              ,    0        (    2    )    W            2      ⁢              i        1              ,          2      ⁢              i        1              ,    1        (    2    )    W                    2        ⁢                  i          1                    +      1        ,                  2        ⁢                  i          1                    +      1        ,    0        (    2    )    W                    2        ⁢                  i          1                    +      1        ,                  2        ⁢                  i          1                    +      1        ,    1        (    2    )  i2 i1 4 5 6 70-15   W                    2        ⁢                  i          1                    +      2        ,                  2        ⁢                  i          1                    +      2        ,    0        (    2    )    W                    2        ⁢                  i          1                    +      2        ,                  2        ⁢                  i          1                    +      2        ,    1        (    2    )    W                    2        ⁢                  i          1                    +      3        ,                  2        ⁢                  i          1                    +      3        ,    0        (    2    )    W                    2        ⁢                  i          1                    +      3        ,                  2        ⁢                  i          1                    +      3        ,    1        (    2    )  i2 i1 89 10 110-15   W            2      ⁢              i        1              ,                  2        ⁢                  i          1                    +      1        ,    0        (    2    )    W            2      ⁢              i        1              ,                  2        ⁢                  i          1                    +      1        ,    1        (    2    )    W                    2        ⁢                  i          1                    +      1        ,                  2        ⁢                  i          1                    +      2        ,    0        (    2    )    W                    2        ⁢                  i          1                    +      1        ,                  2        ⁢                  i          1                    +      2        ,    1        (    2    )  i2i1 12 13 14 150-15   W            2      ⁢              i        1              ,                  2        ⁢                  i          1                    +      3        ,    0        (    2    )    W            2      ⁢              i        1              ,                  2        ⁢                  i          1                    +      3        ,    1        (    2    )    W                    2        ⁢                  i          1                    +      1        ,                  2        ⁢                  i          1                    +      3        ,    0        (    2    )    W                    2        ⁢                  i          1                    +      1        ,                  2        ⁢                  i          1                    +      3        ,    1        (    2    )        Therein    ⁢                  ⁢          W              m        ,                  m          ′                ,        n                    (        2        )              =            1      4        ⁡          [                                                  v              m                                                          v                              m                ′                                                                                                        φ                n                            ⁢                              v                m                                                                                        -                                  φ                  n                                            ⁢                              v                                  m                  ′                                                                        ]      
Table 5 refers to Codebook for 3-layer CSI reporting using antenna ports 15 to 22 (the codebook for 3-layer CSI reporting using 8 antenna ports (ports 15 to 22)), namely, Rank 3 codebook for 8 antenna ports in LTE-A system.
TABLE 5i2 i1 0 1 20-3   W            8      ⁢              i        1              ,          8      ⁢              i        1              ,                  8        ⁢                  i          1                    +      8            (    3    )    W                    8        ⁢                  i          1                    +      8        ,          8      ⁢              i        1              ,                  8        ⁢                  i          1                    +      8            (    3    )        W    ~              8      ⁢              i        1              ,                  8        ⁢                  i          1                    +      8        ,                  8        ⁢                  i          1                    +      8            (    3    )  i2 i1 3 4 50-3       W    ~                      8        ⁢                  i          1                    +      8        ,          8      ⁢              i        1              ,          8      ⁢              i        1                  (    3    )    W                    8        ⁢                  i          1                    +      2        ,                  8        ⁢                  i          1                    +      2        ,                  4        ⁢                  i          1                    +      10            (    3    )    W                    8        ⁢                  i          1                    +      10        ,                  8        ⁢                  i          1                    +      2        ,                  8        ⁢                  i          1                    +      10            (    3    )  i2 i1 6 7 80-3       W    ~                      8        ⁢                  i          1                    +      2        ,                  8        ⁢                  i          1                    +      10        ,                  8        ⁢                  i          1                    +      10            (    3    )        W    ~                      8        ⁢                  i          1                    +      10        ,                  8        ⁢                  i          1                    +      2        ,                  8        ⁢                  i          1                    +      2            (    3    )    W                    8        ⁢                  i          1                    +      4        ,                  8        ⁢                  i          1                    +      4        ,                  8        ⁢                  i          1                    +      12            (    3    )  i2 i1 9 10 110-3   W                    8        ⁢                  i          1                    +      12        ,                  8        ⁢                  i          1                    +      4        ,                  8        ⁢                  i          1                    +      12            (    3    )        W    ~                      8        ⁢                  i          1                    +      4        ,                  8        ⁢                  i          1                    +      12        ,                  8        ⁢                  i          1                    +      12            (    3    )        W    ~                      8        ⁢                  i          1                    +      12        ,                  8        ⁢                  i          1                    +      4        ,                  8        ⁢                  i          1                    +      4            (    3    )  i2 i1 12 13 140-3   W                    8        ⁢                  i          1                    +      6        ,                  8        ⁢                  i          1                    +      6        ,                  8        ⁢                  i          1                    +      14            (    3    )    W                    8        ⁢                  i          1                    +      14        ,                  8        ⁢                  i          1                    +      6        ,                  8        ⁢                  i          1                    +      14            (    3    )        W    ~                      8        ⁢                  i          1                    +      6        ,                  8        ⁢                  i          1                    +      14        ,                  8        ⁢                  i          1                    +      14            (    3    )  i2 i1 150-3       W    ~                      8        ⁢                  i          1                    +      14        ,                  8        ⁢                  i          1                    +      6        ,                  8        ⁢                  i          1                    +      6            (    3    )                                                          Therein              ⁢                                                          ⁢                              W                                  m                  ,                                      m                    ′                                    ,                                      m                    ″                                                                    (                  3                  )                                                      =                                          1                                  24                                            ⁡                              [                                                                                                    v                        m                                                                                                            v                                                  m                          ′                                                                                                                                    v                                                  m                          ″                                                                                                                                                                        v                        m                                                                                                            -                                                  v                                                      m                            ′                                                                                                                                                              -                                                  v                                                      m                            ″                                                                                                                                              ]                                              ,                                                                        W              ~                                      m              ,                              m                ′                            ,                              m                ″                                                    (              3              )                                =                                    1                              24                                      ⁡                          [                                                                                          v                      m                                                                                                  v                                              m                        ′                                                                                                                        v                                              m                        ″                                                                                                                                                        v                      m                                                                                                  v                                              m                        ′                                                                                                                        -                                              v                                                  m                          ″                                                                                                                                ]                                             
Table 6 refers to Codebook for 4-layer CSI reporting using antenna ports 15 to 22 (the codebook for 4-layer CSI reporting using 8 antenna ports (ports 15 to 22)), namely, Rank 4 codebook for 8 antenna ports in LTE-A system.
TABLE 6i2 i1 0 1 20-3   W            8      ⁢              i        1              ,                  8        ⁢                  i          1                    +      8        ,    0        (    4    )    W            8      ⁢              i        1              ,                  8        ⁢                  i          1                    +      8        ,    1        (    4    )    W                    8        ⁢                  i          1                    +      2        ,                  8        ⁢                  i          1                    +      10        ,    0        (    4    )  i2 i1 3 4 50-3   W                    8        ⁢                  i          1                    +      2        ,                  8        ⁢                  i          1                    +      10        ,    1        (    4    )    W                    8        ⁢                  i          1                    +      4        ,                  8        ⁢                  i          1                    +      12        ,    0        (    4    )    W                    8        ⁢                  i          1                    +      4        ,                  8        ⁢                  i          1                    +      12        ,    1        (    4    )  i2 i1 6 70-3   W                    8        ⁢                  i          1                    +      6        ,                  8        ⁢                  i          1                    +      14        ,    0        (    4    )    W                    8        ⁢                  i          1                    +      6        ,                  8        ⁢                  i          1                    +      14        ,    1        (    4    )        Therein    ⁢                  ⁢          W              m        ,                  m          ′                ,        n                    (        4        )              =            1              32              ⁡          [                                                  v              m                                                          v                              m                ′                                                                        v              m                                                          v                              m                ′                                                                                                        φ                n                            ⁢                              v                m                                                                                        φ                n                            ⁢                              v                                  m                  ′                                                                                                        -                                  φ                  n                                            ⁢                              v                m                                                                                        -                                  φ                  n                                            ⁢                              v                                  m                  ′                                                                        ]      
Table 7 refers to Codebook for 1-layer CSI reporting using antenna ports 15 to 22 (the codebook for 5-layer CSI reporting using 8 antenna ports (ports 15 to 22)), namely, Rank 5 codebook for 8 antenna ports in LTE-A system.
TABLE 7i2 i1 00-3       W          i      1              (      5      )        =            1              40              ⁡          [                                                  v                              2                ⁢                                  i                  1                                                                                        v                              2                ⁢                                  i                  1                                                                                        v                                                2                  ⁢                                      i                    1                                                  +                8                                                                        v                                                2                  ⁢                                      i                    1                                                  +                8                                                                        v                                                2                  ⁢                                      i                    1                                                  +                16                                                                                        v                              2                ⁢                                  i                  1                                                                                        -                              v                                  2                  ⁢                                      i                    1                                                                                                          v                                                2                  ⁢                                      i                    1                                                  +                8                                                                        -                              v                                                      2                    ⁢                                          i                      1                                                        +                  8                                                                                        v                                                2                  ⁢                                      i                    1                                                  +                16                                                        ]      
Table 8 refers to Codebook for 1-layer CSI reporting using antenna ports 15 to 22 (the codebook for 6-layer CSI reporting using 8 antenna ports (ports 15 to 22)), namely, Rank 6 codebook for 8 antenna ports in LTE-A system.
TABLE 8i2 i1 00-3       W          i      1              (      6      )        =            1              48              ⁡          [                                                  v                              2                ⁢                                  i                  1                                                                                        v                              2                ⁢                                  i                  1                                                                                        v                                                2                  ⁢                                      i                    1                                                  +                8                                                                        v                                                2                  ⁢                                      i                    1                                                  +                8                                                                        v                                                2                  ⁢                                      i                    1                                                  +                16                                                                        v                                                2                  ⁢                                      i                    1                                                  +                16                                                                                        v                              2                ⁢                                  i                  1                                                                                        -                              v                                  2                  ⁢                                      i                    1                                                                                                          v                                                2                  ⁢                                      i                    1                                                  +                8                                                                        -                              v                                                      2                    ⁢                                          i                      1                                                        +                  8                                                                                        v                                                2                  ⁢                                      i                    1                                                  +                16                                                                        -                              v                                                      2                    ⁢                                          i                      1                                                        +                  16                                                                        ]      
Table 9 refers to Codebook for 1-layer CSI reporting using antenna ports 15 to 22 (the codebook for 7-layer CSI reporting using 8 antenna ports (ports 15 to 22)), namely, Rank 7 codebook for 8 antenna ports in LTE-A system.
TABLE 9i2  i1  00-3       W          i      1              (      7      )        =            1              56              ⁡          [                                                  v                              2                ⁢                                  i                  1                                                                                        v                              2                ⁢                                  i                  1                                                                                        v                                                2                  ⁢                                      i                    1                                                  +                8                                                                        v                                                2                  ⁢                                      i                    1                                                  +                8                                                                        v                                                2                  ⁢                                      i                    1                                                  +                16                                                                        v                                                2                  ⁢                                      i                    1                                                  +                16                                                                        v                                                2                  ⁢                                      i                    1                                                  +                24                                                                                        v                              2                ⁢                                  i                  1                                                                                        -                              v                                  2                  ⁢                                      i                    1                                                                                                          v                                                2                  ⁢                                      i                    1                                                  +                8                                                                        -                              v                                                      2                    ⁢                                          i                      1                                                        +                  8                                                                                        v                                                2                  ⁢                                      i                    1                                                  +                16                                                                        -                              v                                                      2                    ⁢                                          i                      1                                                        +                  16                                                                                        v                                                2                  ⁢                                      i                    1                                                  +                24                                                        ]      
Table 10 refers to Codebook for 1-layer CSI reporting using antenna ports 15 to 22 (the codebook for 8-layer CSI reporting using 8 antenna ports (ports 15 to 22)), namely, Rank 8 codebook for 8 antenna ports in LTE-A system.
TABLE 10i2  i1 00                                           W                          i              1                                      (              8              )                                =                                                          1            8                    ⁡                      [                                                                                v                                          2                      ⁢                                              i                        1                                                                                                                                  v                                          2                      ⁢                                              i                        1                                                                                                                                  v                                                                  2                        ⁢                                                  i                          1                                                                    +                      8                                                                                                            v                                                                  2                        ⁢                                                  i                          1                                                                    +                      8                                                                                                            v                                                                  2                        ⁢                                                  i                          1                                                                    +                      16                                                                                                            v                                                                  2                        ⁢                                                  i                          1                                                                    +                      16                                                                                                            v                                                                  2                        ⁢                                                  i                          1                                                                    +                      24                                                                                                            v                                                                  2                        ⁢                                                  i                          1                                                                    +                      24                                                                                                                                        v                                          2                      ⁢                                              i                        1                                                                                                                                  -                                          v                                              2                        ⁢                                                  i                          1                                                                                                                                                          v                                                                  2                        ⁢                                                  i                          1                                                                    +                      8                                                                                                            -                                          v                                                                        2                          ⁢                                                      i                            1                                                                          +                        8                                                                                                                                  v                                                                  2                        ⁢                                                  i                          1                                                                    +                      16                                                                                                            -                                          v                                                                        2                          ⁢                                                      i                            1                                                                          +                        16                                                                                                                                  v                                                                  2                        ⁢                                                  i                          1                                                                    +                      24                                                                                                            -                                          v                                                                        2                          ⁢                                                      i                            1                                                                          +                        24                                                                                                                  ]                                 
In the above tables, φn=ejπn/2, νm=[1 ej2πm/32 ej4πm/32 ej6πm/32]T, therein, (•)T represents matrix transpose.
In the case of no codebook compression, PMI is defined as follows:
For 8 antenna ports and corresponding RI value which is 1, the first PMI value i1ε{0, 1, 2, . . . , 15} shall correspond to the codebook index i1 in Table 3 and the second PMI value i2ε{0, 1, 2, . . . , 15} shall correspond to the codebook index i2 in Table 3.
For 8 antenna ports and corresponding RI value which is 2, the first PMI value i1ε{0, 1, 2, . . . , 15} shall correspond to the codebook index i1 in Table 4 and the second PMI value i2ε{0, 1, 2, . . . , 15} shall correspond to the codebook index i2 in Table 4.
For 8 antenna ports and corresponding RI value which is 3, the first PMI value i1ε{0, 1, 2, 3} shall correspond to the codebook index i1 in Table 5 and the second PMI value i2ε{0, 1, 2, . . . , 15} shall correspond to the codebook index i2 in Table 5.
For 8 antenna ports and corresponding RI value which is 4, the first PMI value i1ε{0, 1, 2, 3} shall correspond to the codebook index i1 in Table 6 and the second PMI value i2ε{0, 1, 2, . . . , 15} shall correspond to the codebook index i2 in Table 6.
For 8 antenna ports and corresponding RI value which is 5, the first PMI value i1ε{0, 1, 2, 3} shall correspond to the codebook index i1 in Table 3 and the second PMI value i2ε{0} shall correspond to the codebook index i2 in Table 7.
For 8 antenna ports and corresponding RI value which is 6, the first PMI value i1ε{0, 1, 2, 3} shall correspond to the codebook index i1 in Table 4 and the second PMI value i2ε{0} shall correspond to the codebook index i2 in Table 8.
For 8 antenna ports and corresponding RI value which is 7, the first PMI value i1ε{0, 1, 2, 3} shall correspond to the codebook index i1 in Table 5 and the second PMI value i2ε{0} shall correspond to the codebook index i2 in Table 9.
For 8 antenna ports and corresponding RI value which is 8, the first PMI value i1ε{0} shall correspond to the codebook index i1 in Table 6 and the second PMI value i2ε{0} shall correspond to the codebook index i2 in Table 10.
LTE-A system supports PUCCH reporting mode 1-1 for 8 antenna ports to achieve the feedback for RI, wideband PMI and wideband CQI. At present, there are two PUCCH reporting mode 1-1, respectively, referred to as submode 1 and submode 2. In submode 2, RI is reported on an individual sub-frame, the first PMI, the wideband second PMI and the wideband CQI is needed to be reported in a sub-frame; the Uplink Control Information (UCI) domain that first PMI, wideband second PMI and wideband CQI report may be shown in Table 11 or Table 12.
TABLE 11The number of bits2 antenna ports4 antenna ports8 antenna portsDomainRank = 1Rank = 2Rank = 1Rank >1Rank = 1Rank >1wideband CQI444444Spatial030303differencingCQIThe first PMI————TBDTBDvalueThe wideband2144TBDTBDsecond PMIvalue
TABLE 12The number of bits2 antenna ports4 antenna ports8 antenna portsDomainRank = 1Rank = 2Rank = 1Rank >1Rank = 1Rank >1wideband CQI444444Spatial differencing030303CQIwideband PMI2144TBDTBD
TBD refers that it is not defined in current standard.
The total number of the bits in the domain cannot exceed 11. For 8 antenna ports:
When Rank=1, a total of 8 bits are required for the first PMI value and the second PMI value in Table 3, and there will be 12 bits in total plus 4 bits of wideband CQI, beyond 11 bits.
When Rank=2, a total of 8 bits are required for the first PMI value and the second PMI value in Table 4, and there will be 15 bits in total plus 4 bits of wideband CQI and 3 bits of spatial differencing CQI, beyond 11 bits.
When Rank=3, a total of 6 bits are required for the first PMI value and the second PMI value in Table 5, and there will be 13 bits in total plus 4 bits of wideband CQI and 3 bits of spatial differencing CQI, beyond 11 bits.
When Rank=4, a total of 5 bits are required for the first PMI value and the second PMI value in Table 6, and there will be 12 bits in total plus 4 bits of wideband CQI and 3 bits of spatial differencing CQI, beyond 11 bits.
LTE-A system further supports PUCCH reporting mode 2-1 for 8 antenna ports to achieve the feedback for the RI, the wideband first PMI, the wideband second PMI and the feedback for CQI or RI, the wideband second PMI, wideband CQI, the sub-band second PMI and sub-band CQI based on Precorder Type Indication (PTI); the uplink control information domain that wideband PMI and wideband CQI report is shown in Table 13.
TABLE 13The number of bits8 antenna portsRank = 1Rank = 2, 3Rank = 4Rank = 5, 6, 7Rank = 8DomainPTI = 0PTI = 1PTI = 0PTI = 1PTI = 0PTI = 1PTI = 0PTI = 1PTI = 0PTI = 1wideband4040404040CQIsub-band0404040404CQISpatial0033333333differencingCQIWideband4040300000i2Sub-band i20402020000Sub-band01 or 201 or 201 or 201 or 201 or 2label
The total number of the bits in the domain cannot exceed 11. For 8 antenna ports:
When Rank=2, a total of 4 bits are required for the second PMI value in Table 4, and there will be 13 bits in total plus 4 bits of sub-band CQI, 3 bits of spatial differencing CQI and at most 2 bits of sub-band location indicator, beyond 11 bits.
When Rank=3, a total of 4 bits are required for the second PMI value in Table 5, and there will be 13 bits in total plus 4 bits of sub-band CQI, 3 bits of spatial differencing CQI and at most 2 bits of sub-band location indicator, beyond 11 bits.
When Rank=4, a total of 3 bits are required for the second PMI value in Table 6, and there will be 12 bits in total plus 4 bits of sub-band CQI, 3 bits of spatial differencing CQI and at most 2 bits of sub-band location indicator, beyond 11 bits.
Codebook compression shall be required for all situations mentioned above; in case of codebook compression, the relationship of the first PMI value and the wideband second PMI value with the codebook indexes i1 and i2 shall be redefined. Currently, no relationship definition of the first PMI value and the wideband second PMI value with the codebook indexes i1 and i2 or that of PMI with the codebook indexes i1 and i2 after codebook compression is provided.
In the procedure of realizing the objects of the present invention, at least the following problems existing in the current technologies were found:
At present, no relationship definition of the first PMI value and the wideband second PMI value with the codebook indexes i1 and i2 or that of PMI with the codebook indexes i1 and i2 after codebook compression is provided.